Method of cutting mains under pressure



May 30, 1944., G. E. STEUDEL METHOD 0F CUTTING MAINS UNDER PRESSURE Filed Dec. 11', 1941 s Sheets-Sheet 1 JF'IE-1- FIG. :3;

.1 [7206)?!07. & 650 965 A. 57500.42, f

G. E. STEUDEL METHOD OF CUTTING MAINS UNDER PRESSURE- May 30, 1944.

Filed Dec. 11, 1941 3 Sheets-Sheet 2 May 30, 1944. 'a. E. STEUDEL METHOD OF CUTTING MAINS UNDER PRESSURE Filed D90. 11, 1941 3 Sheets-Sheet 5 FIE-1.7.,

Patented May 30, 1944 METHOD OF CUTTING MAINS UNDER PRESSURE George E. Steudel, Chicago, Ill.

Application December 11, 1941, Serial No; 422,600

Claims.

The present invention relatesto an improved method for cutting out. sections of gas mains and replacing new sections while gas pressure is maintained in the mains.

7 While not limited thereto, the method is well suited for removing weakened or dangerous sections from gas mains of enormous size, .such as those used in connection'with blast furnace equipment for conveying blast furnace gas to soaking pits, boiler house plants, stoves or other related blast furnace or steel mill equipment.

Such blast furnace equipment frequently includes in the gas line a water seal in the nature of a huge S-shaped trap which at intervals requires replacement. In a typical blast furnace installation, the gas main for conveying blast furnace gas is built up of steel plate and is of exceeding-1y large diameter, for example, in the neighborhood of 6 to 8 feet. To remove a damaged or weakened Water seal involves the removal of a length of about 46 feet of such large diameter main. Since many auxiliary pieces of equipment, such as boilers. stoves, soaking pits and the like are fired by blast furnace gas, it is important that at the time of removal of a trap or other weakened section of the main that gas pressure be not entirely out off from the main, or if the pressure is reduced or cut ofi, that the same be interrupted for only a very short length of time. The method to be presently described solves the problem very eiiectively.

The invention will be fully apparent from the following detailed disclosure when read in connection with the accompanying drawings and will be defined with particularity in the appended claims. i

In the drawings:

Figure 1 represents a length of a blast furnace gas main approximately 8 feet in diameter, showing a trap or water seal section between the lines A--A and B-B which is to be severed from the main and replaced by a new section;

Figure 2 is a View similar to Figure 1 showing subsequent steps in the method;

Figure 3 is an enlarged longitudinal section illustrative of the steps ofcutting the main along the face of the permanent flange, preferably in increments of 2 feet, at line A-A or B-B of Figure 1; 3

Figure 4 is a view similar to Figure 3, illustrat-' ing the next cutting step after the previous cutting increment has beenpacked, bolts installed in the flanges over the packing, and packing wedged in place; l

Figure 4a is a detail section taken on line IVa-IVa of Figure 4;

Figures 5, 6 and 7 are sectional views illus: trating further steps in the method; and t Figure 8 is a section on line VIII-VI1I of Figure 7 showing a goggle valv or sealing plate in open position and which may be moved to a closed position illustrated in section in Figure 6.

Referring in detail to Figure 1 of the draw-' ings, the first step in the method compriseswelcling permanent flanges Illa and lllb. to the portions A and B of the main. adjacent the lines A-A and B- B which are to remain in place. These flanges llla and lb are of sectional form,

'" being split along a diametric line so as to facilie section of the main to be removed. In the drawings illustrating "the invention, this section of the main to be removed includes the S-shaped trap, designated by the numeral M. This trap is part of conventional blast furnace equipment and normally contains water to form a seal between different sections of the main. It is' clear. however, that the method is equally applicable to removing straight lengths of a main; The per manent flanges HM and lllb and temporary flanges I2a and 12b, after being welded in place, are substantially parallel.

The next step in the method is to weld 1'6? spective sectional rings Ito and 15b tothe section of main to be removed atlocations inter mediate the flanges Ida and I20, and illb and I22 These rings are of split or sectional form to fa-' cilitate ready attachment, as by welding, to the exterior or the portion of the main to be removed.

rings lfib, define annular spaces in the zone where the main is to be severed. Thus theflflanges and the rings serve to define the cutting zone or re gion of cleavage.

The next step in the method is to cut the main along the face and slightly under the heel of the permanent flange Illa, preferably in increments of 2. feet,such as indicated at l8 in'Figg After the main is out (one increment),

It will be understood that the flanges Illa and rings I611, as well as the flanges Hlband Over up, as illustrated in Figure 4. Wooden wedges 24 are placed between the bolts 26 and packing 22 to hold the packing in place and to prevent the escape of gas. This procedure is continued until the entire circumference of the main is cut, packed, and. bolted tight. Similarly, the gas main between flanges lllb and l6b is cut, packed, and bolted. By the above procedure, the main is circumferentially cut at lines A--A and BB in Figure 1,'which severs section of gas main I4 from main A and B in Figure 1.

It is apparent that the severed section of the main to be ultimately removed is nevertheless so sealed by the packing as to prevent the escape of gas. The bolts 26 serve to hold the severed section in place until its removal is to be effected.

The problem at this stage is to remove the section of main between the lines A-A and BB amount of interference with normal operation of the apparatus connected on the parts of the main beyond the section lines A.A and BB, and with a minimum loss of gas from the main of enormous diameter.

To accomplish this desirable end I next attach sealing plates or goggle valves 28, such as indicated in Figure 8, to the permanent flanges la and Iflb. Each sealing plate or goggle valve has a blanking off or closureportion 30 and an aperture. or port 32. Each gogglevalve or sealing plate is connected by bolts 28 to. the adjacent permanent flange. It will be understood that when in one position the solid portion 3-5! will serve as abarrier to prevent flow of gas through the main. Thi position is shown in Figure 5. When the sealing plate is secured in its other position, shown in Figure 7, the gas may flow through the port 32 thereof. These goggle valves or sealing plates are assembled in relation to the flanges Illa and lb prior to the removalof all the bolts 26 which couple the permanent flanges lfla with the'temporary flanges iZa secured to the section of main to be removed. After the sealing plates or goggle valves are as sembled in readiness to be quickly moved to closed position, the pressure on the gas main is reduced. Thereupon all of the bolts 25 are removed and the section of the main between the points A-A and BB of Figure 1 is bodily removed and the goggle valves or sealing plates are moved to such position that the closure portions 30 thereof serve as barriers to prevent the escape of gas from the sections A and B of the main. Thereafter, a new section of main is installed between the lines A-A and BB of Figure 1. This new section, designated at l5 in Figure 6, has

at its ends flanges l2a and I2?) adapted to be bolted to the permanent flanges Illa and lbb.

In order to maintain a substantially uniform and controlled pressure in the part of the main severed from the source of gas during the course of constructing the new main, an eight inch bypass pipe line. 50, with a gate valve 52 therein, is preferably installed. This procedure insures controlled gas pressure in the isolated part of the main and thereby eliminates the possibility of air infiltration into this part of the system.

While. the new section of main is being installed between the permanent flanges Ilia and Nib, air is introducedinto the said new section of main through a suitable hole thereinunder ,superatmospheric pressure, the hole being later closed by a plug. This step of introducing a positive current of air eliminates the possibility of any gas accumulation in the newly constructed main and therefore makes safe the conventional welding method. During the cutting of the main, high pressure air is also directed over the point of out to remove gas accumulations that may interfere with operations. The cutting is done by the use of an oxyacetylene or similar metal buming torch, or may also be accomplished with an electric arc type of cutting tool.

After the new section of main has been bolted in place, the goggle valve or sealing plate 28 is shifted so as to bring the port 32 into alignment 7 with the contiguous sections of the main so as to thus open communication between the sections A and B, thus restoring communication between them.

All of the above steps, it will be understood, are carried out Without materially interfering with the normal gas pressure in the main and Without loss of a large quantity of gas such as would be contained in a main having a diameter in the neighborhood of 8 feet.

The invention has been specifically described with reference to removing a damaged section of a gas main and inserting a new section therein. It will be understood, however, that the same procedure may be followed in renewing weakened or damaged sections of steam mains, water mains or the like. Thus the invention is applicable to cutting and replacing sections of any main adapted to carry any type of fluid under pressure.

While I have described quite precisely a certain preferred sequence of operations, it is to be understood that the drawings and descriptive matter are to be interpreted in an illustrative rather than a limiting sense, since various modifications may be made without departure from the invention as defined in the appended claims.

I claim:

3.. The method of cutting a section from a main containing a fluid under pressure and inserting a new section therein, which includes the steps of cutting through the wall of the main in separate peripheral increments to form one zone of cleavage, applying a packing after each increment is cut to prevent the escape of fluid from the main, then at a second zone of cleavage spaced from the first mentioned zone, repeating the aforesaid steps to thus completely sever from the main the section thereof between said zones, removing the packings at both zones of cleavage, applying a respective temporary sealing member to the main at eael: of said zones of cleavage, removing the severed section, inserting a new section of main, connecting the ends of said new section to the main, and removing the said temporary sealing members, to thus establish communication through said new section. V

2. The method of cutting a section from a main containing a fluid under pressure and inserting a substitute section therein, which comprises securing permanent members in juxtaposition to the zones where the main is to be sev- 'ered, securing temporary members to the section of the main to be removed at points spaced from said permanent members, securing respective ring sectors to the section of the main to be removed intermediate said permanent members and said temporary members, making a respective series of cuts in separate increments in the main in the region immediately adjacent each of said permanent members, closing the resulting void after each increment is cut away soas to prevent the fluid from escaping therethrough, the extent of and number of said cuts made being sufiicient to completely sever the main adjacent each of said permanent members, sealing the ends of the sections of the main which are to remain in place, removing the severed section of the main, inserting a new section of main and securing it to said permanent members, and finally unsealing said ends, thus restoring communication between the permanent sections of the main through the said newly inserted section.

3. The method of cutting a section from a main containing fluid under pressure and inserting a new section therein, which comprises securing permanent flanges in juxtaposition to the zones where the main is to be severed, securing temporary flanges to the section of the main to be removed at points spaced from said permanent flanges, securing respective rings to the section of the main to be removed intermediate said permanent flanges and said temporary flanges, coupling said permanent flanges to said temporary flanges, cutting in separate increments a series of openings in the periphery of the main in the region adjacent each of said permanent flanges, inserting packing between the permanent flanges and said rings so as to prevent the fluid from escaping through said openings, thus severing the main adjacent each of said permanent flanges, securing respective apertured sealing plates to the permanent flanges in positions to close the sections of the main which are to remain in place, uncoupling said permanent flanges from said temporary flanges, removing the severed section of the main between said sealing plates, inserting a new section of main and securing the ends thereof to said permanent flanges, and moving each sealing plate to a position where the aperture therein will establish communication between the permanent sections of the main and the said newly inserted section.

4. The method of cutting a section from a main containing fluid under pressure and inserting a new section therein, which comprises securing permanent flanges in juxtaposition to the zones where the main is to be severed, securing temporary flanges to the section of the main to be removed at points spacedfrom said permanent flanges, securing respective rings to the section of the main to be removed intermediate said permanent flanges and said temporary flanges, cutting in separate increments a series of openings in the periphery of the main in the region adjacent each of said permanent flanges, inserting bolts to couple the permanent flanges to the temporary flanges, inserting packing between the permanent flanges and said rings so as to prevent the fluid from escaping through said perforations and inserting wedges between said bolts and packing to compressively confine the latter in the annular space between the permanent flanges and said rings to thus efiectively seal the series of perforations, the cuts being of a number suflicient to sever the main adjacent each of said permanent flanges, sealing the ends of the main at the respective zones of cleavage, removing said bolts to uncouple said permanent flanges from said temporary flanges, removing the section of main between said permanent flanges, and inserting a new section of main and securing it to said permanent flanges.

5. The method of cutting a section from a main containing a fluid under pressure and inserting a new section therein, which includes the steps of cutting through the wall of the main in separate increments to form one zone of cleavage, applying a closure after each increment is cut away to prevent the escape of fluid from the main, then at a second zone of cleavage spaced from the first named zone, repeating the aforesaid steps to thus completely sever from the main the section thereof between said zones, removing the said closures at both zones of cleavage, applying a respective temporary sealing member to the main at said zones of cleavage, removing the severed section between said zones, inserting a new section of main, introducing air under superatmospheric pressure into the new section so as to exclude the flow of fluid thereinto, removing the said temporary sealing members, and connecting the ends of said new section to the main, to thus establish communication through said new section.

GEORGE E. STEUDEL. 

